The present application relates to a piezoelectric device that detects a rotational angular velocity of a subject, an oscillation type gyro sensor in which a piezoelectric device is mounted, an electronic device in which an oscillation type gyro sensor is mounted, and a method of manufacturing a piezoelectric device.
As commercially used angular velocity sensors, so-called oscillation type gyro sensors have been widely used. An oscillation type gyro sensor is a sensor having a cantilevered oscillator that oscillates at a predetermined resonance frequency and a piezoelectric device that detects the Coriolis force that occurs due to an influence of an angular velocity so as to detect the angular velocity (for example, see Japanese Patent Application Laid-Open No. 2001-165664, paragraph 0043, FIG. 1, hereinafter this document is referred to as Patent Document 1).
An oscillation type gyro sensor has advantages of for example simple mechanism, short activation time, and low manufacturing cost. Oscillation type gyro sensors are mounted in electronic devices such as video cameras, virtual reality devices, and car navigation systems for sensors that detect hand jitter, motion detection, and direction detection, respectively.
In recent years, as electronic devices in which an oscillation type gyro sensor is mounted have been size-reduced and have had improved functions, needs of size-reduction and advanced functions of the oscillation type gyro sensors have become strong. For example, to satisfy the needs of multi-functions and size-reduction of an electronic device, an oscillation type gyro sensor is mounted on a single circuit board together with other sensors. To accomplish the size-reduction of the electronic device, a technique called the MEMS (Micro Electro Mechanical System) that forms a structure on an Si substrate using a thin film process and a photolithography technique has become common.